#!/usr/bin/env python
# -*- encoding: utf-8 -*-
class XDB2_2_PY(object):

    @staticmethod
    def substr(p_str=None, p_start=1, p_len=0):
        p_start = p_start - 1
        end = p_start + p_len
        rst = p_str[p_start:end]
        return rst

    @staticmethod
    def nvl(p_expr1=None, p_expr2=None):
        rst = p_expr1 if p_expr1 is not None else p_expr2
        return rst
